Perhaps down drug administered to old men (8)
I believe the answer is:
feathers
'perhaps down' is the definition.
(I know that down feather is a type of feathers)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for feathers that I've seen before include "Covering for birds" , "Possibly down" , "growth of birds" , "Bird insulation" , "Plumage, insulation for birds" .)